Thread pull-off and wiping mechanism for sewing machines

ABSTRACT

A thread pull-off and wiping mechanism for sewing machines in which thread-engaging pull-off and thread wiping elements are reciprocated by a spring-returned linkage that may be detained in an inoperative position by a latch device, which, when released permits the linkage to assume an operative relation to a drive element operating in timed relation with the sewing machine thread take-up mechanism.

United States Patent 1 Oct. 3, 1972 Papajewski et al.

[54] THREAD PULL-OFF AND WIPING MECHANISM FOR SEWING MACHINES [72] Inventors: Reinhold Papaiewski, Buchig;

Johann O. Kleinschmidt, Blankenloch, Buchig, both of Germany [73] Assignee: The Singer Company, New York,

[22] Filed: June 4, 1971 [21] Appl. No.: 149,968

[52] US. Cl ..ll2/243 [51] Int. Cl. ..D05b 49/00 [58] Field of Search ..1 12/242, 243, 248, 241, 252

[56] References Cited UNITED STATES PATENTS 3,028,824 4/1962 Parry et a1. ..1 12/241 3,498,243 3/1970 Aoyama ..1 12/252 3,601,074 8/1971 Hagen ..l12/252 3,584,589 6/1971 Pirrello ..1 12/252 2,977,909 4/1961 Neukirch 1 12/241 Primary Examiner-Jordan Franklin Assistant Examiner-George l-l. Krizmanich Attorney-Marshall J. Breen, Chester A. Williams, Jr. and Robert E. Smith A 571 ABSTRACT A thread pull-off and wiping mechanism for sewing machines in which thread'engaging pull-off and thread wiping elements are reciprocated by a spring-returned linkage that may be detained in an inoperative position by a latch ievice, which, when released permits the linkage to assume an operative relation to a drive element operating in timed relation with the sewing machine thread take-up mechanism.

8 Claims, 5 Drawing Figures PATENTEUum 3 1972 SHEEI 2 OF 2 INVENTORS. Relnhold Papojewski BY Johann QKleinschmidt ;l @W

ATTORNEY THREAD PULL-OFF AND WIPING'MECHANISM FOR SEWHNG MACH-WES BACKGROUND OF THE INVENTION The thread pull-off and wiping mechanism of thisinvention is intended to operate upon a sewing thread at the conclusion of a sewing operation so that the thread will not be left extending through a work piece in which case it might be snubbed therein and abnormally drawn out when the work piece is removed, and so that sufiicient slack thread is introduced to permit the next seam to be started without danger of unthreading the needle.

Previously know thread pull-off and wiping mechanisms of this type have been employed on sewing machines which operate in a predetermined cycle of stitches, such as button and buttonhole machines, tackers and the like, to wipe and pull off thread between each sewing cycle, and it has been known to operate such thread pull-off and thread wipers by operative association with the work clamp opening mechanism of the cyclically operated machines. These known thread pull-off and thread wiping mechanisms would, therefore, not be usable on non-cyclic sewing machines because the pull-off and wiping action on the thread is not desired in these non-cyclic machines every time the sewing is stopped.

SUMMARY OF THE INVENTION It is an object of this invention to provide a thread pull-off and wiping mechanism which may be applied either to cyclic or non-cyclic sewing machines. This object is attained by providing a linkage for operating the thread pull-off and wiper, which linkage may be latched out of cooperative engagement with a drive element which is associated in timed relationship with the sewing machine thread take-up mechanism. The thread pull-off and wiper is not actuated each time the sewing machine stops, but only when the latch is released and, therefore, this mechanism has application to all types of sewing machines.

It is another advantageous feature of this invention that the command or signal to initiate thread pull-off and thread wiping, by releasing the latch discussed above, may be given at any time during the last stitch forming operation of the sewing machine. The timing of such signal or command is not critical since it is the ensuing engagement with the drive element which will operate the thread pull-off and thread wiping mechanism.

A further object and advantage of this invention is provided by the cooperative interrelation of the drive element for the thread pull-off and thread wiper with the sewing machine thread take-up mechanism. By this arrangement, the various instrumentalities which have manipulative influence on the thread can be arranged to operate in concert rather than at cross purposes.

DESCRIPTION OF THE DRAWINGS This invention will be described hereinbelow with reference to a preferred form illustrated in the accompanying drawings in which:

FIG. 1 represents as end elevational view of the head end portion of a sewing machine with portions of the sewing machine frame broken away to expose the thread pull-off and thread wiping mechanism of this invention in an at-rest position,

FIG. 2 is a side elevational view of the sewing machine head end portion of FIG. 1 with portions of the machine frame broken away,

FIG. 3 is an end elevationalview of a fragment of the head end portion of the sewing machine illustrated in FIG. 1 but showing the actuating link for the thread pull-off and thread wiping mechanism released and occupying a position of readiness to be operated,

FIG. 4 is an end elevational view of the head end portion of the sewing machine of FIG. 1 but showing the thread pull-ofi and thread wiping mechanism shifted to an extreme position by the sewing machine actuating mechanism, and

FIG. 5 is a side elevational view of a fragment of the head end portion of the sewing machine'illustrating the thread pull-off and thread wiping mechanism in the extreme position shown in FIG. 4.

As illustrated in the drawings, this invention is shown as'applied to a lockstitch zigzag sewing machine of the type known in the art as a Model 457G Machine manufactured by The Singer Company. In the drawings a portion of the sewing machine bracket arm is indicated at 11 particularly showing the sewing head extremity thereof. Journalled for endwise reciprocation in the sewing head is a needle bar 12 which carries an eyepointed thread carrying needle 13. Also carried in the sewing head is a bushing 14 in which is endwise shiftably supported a presser bar 15 carrying at its lower extremity a presser foot 16. The bushing 14 may be secured by any suitable means in the sewing head, as for instance, by a force fit therein, and the presser bar is biased downwardly as by a leaf spring 17 within the sewing machine bracket arm.

As shown in FIG. 4, a main shaft 20 is carried in the sewing machine bracket arm and has secured thereto a counterbalance 21 and a crank 22 which is embraced by a drive link 23 pivotally connected to the needle bar 12. The sewing head portion of the sewing machine bracket arm is closed by an end cover plate 24 secured thereon by fastening screws 25. The end cover plate is formed with a circular aperture accommodating with slight clearance a take-up support disk 27 which is carried on the crank 22 but is arranged co-axially of the main shaft 20. Fastened to the support disk 27, as by fastening screws 28, is a rotary thread take-up member 29. The rotary take-up member 29 is well-known in the sewing machine art having been used extensively on the aforementioned Model 4576 Machine. As shown in the drawings the take-up element is encased by a protecting shroud 30 with a swing-up cover member 31. As best shown in'FIG. l the needle thread is directed from a source of supply through a thread guide 32 to the take-up member 29, then to a thread guide 33 on the end cover plate 24 immediately above the needle bar 12, then to a thread guide 34 on the needle bar and finally to the needle 13. It is a well-known function of the take-up member to draw up and pay out quantities of the needle thread as required in the formation of stitches.

The thread pull-off and wiping mechanism of this invention is intended to be used on a sewing machine which has a mechanism for severing the needle thread beneath the work at the end of a stitched seam. Such thread trimming mechanism, which is referred to in the art as an underbed thread trimming mechanism, does not form a direct part of this invention and any known underbed thread trimming may be utilized. When the needle thread is severed beneath the work it is desirable to wipe the severed thread from the work before the work can be removed from the sewing machine because if it is not so wiped the needle thread-end leading back to the thread supply may become caught in the work resulting in an abnormally long thread end being pulled through the eye of the needle. The pull-off of the needle thread is desirable immediately before the needle thread is severed in order that sufficient needle thread will be provided from the needle eye to the severed end so that the next line of stitches can be started without the necessity of rethreading the needle. The needle thread pull-off and wiping mechanism of this invention provides a simple and effective construction in which the pull-off and wiping functions will always be timed to occur in appropriate relation to the other sewing machine operations so as to result in the desired manipulation of the needle thread.

1 The needle thread pull-off of this invention is performed by a wire thread-engaging element 40 which is clamped by a fastening screw 41 to a lever 42 pivoted on a fulcrum pin 43 exteriorly on the end cover plate 24. The wire thread-engaging element 40 is formed with a loop 44 on its free extremity which in the first or at-rest extreme position, as is shown in FIG. 1, loosely embraces the thread path between the thread guides 33 and 34. In the opposite extreme position as shown in FIG. 4, the lever 42 is turned to bring the loop 44 well forwardly of the thread guides 33 and 34 so as to pull off a loop in the needle thread between these two thread guides. i

The needle thread wiper of this invention is supported on a block 50 which is fastened to the presser bar bushing 14 beneath the sewing machine bracket arm. A wiper supporting lever 51 is formed with bifurcated arms embracing the block 50 and fulcrumed thereto by the pin 52. An extension 53 of one of the bifurcated lever arms accommodates a fastening screw 54 by which is secured a wire thread engaging element 55 including a hook-shaped thread-engaging extremity 56.

A connecting member 60 is attached by a pivot pin 61 to the bifurcated lever 51 at the opposite side of the fulcrum pin 52 from the thread-engaging element 55. The connecting member 60 is also pivoted by a pin 62 to one arm of a bell crank lever 63 which is carried exteriorly of the end cover plate 24 on a fulcrum pin 64 secured by a threaded fastener 65 to the end cover plate. The opposite arm of the bell crank lever 63 carries a pin 66 which is embraced in a slot 67 formed in the thread pull-off carrying lever 42. The linkage 42, 60, 63 on the outside of the end cover plate 24 may be kept from interfering with the thread by a protective plate 68 shown in phantom lines in FIG. 1 which may be held on the end cover plate by a fastening screw 69.

The thread wiper and thread pull-off will thus always operate simultaneously and when the thread pull-off member occupies the first extreme position as shown in FIG. 1 the thread wiper element will occupy a first extreme position substantially at right angles to the needle and as shown in FIG. 2. When the thread pull-off element occupies the second extreme position as shown in FIG. 4, the thread wiper element will occupy a second extreme position as shown in FIG. at the opposite side of the needle from that illustrated in FIG. 2.

The pivot pin 62 by which the connecting member 60 is attached to the bell crank lever 63 passes through an arcuate clearance slot 70 in the end cover plate 24 and interiorly of the end cover plate the pivot pin 62 is connected to a drive link 71 which extends substantially tangentially of the take-up support disk 27. The drive link 71 near the upper free extremity is formed with a lateral projection 72 defining a cam engaging surface 73 which extends substantially radially of the take-up support disk. Above the lateral projection 72 the edge of the drive link facing the take-up supporting disk 27 is formed with a curved recess 74 defining a latch cooperating edge 75 adapted to cooperate with a latch pin 76. Preferably the latch pin 76 comprises the armature of an electrical solenoid, indicated generally at 77, which is secured by a bracket 78 inside the end cover plate 24. The latch pin 76 is biased by a compression spring 79 into an extended position toward the left, as viewed in FIG. 2. When the solenoid is energized, the latch pin 76 will be shifted into a retracted position toward the right, as viewed in FIG. 2.

A coil spring is arranged in tension between a pin 91 set into the drive link 71 and a pin 92 carried on the inside of the end cover plate. The pin 92 may be provided as a head formed on the threaded fastening screw 65 for the bell crank fulcrum pin 64. As shown in FIGS. 1 and 4, the tension spring 90 is arranged relatively to the pivot pin 62 for the drive link 71 so as to exert two components of force on the drive link. First, the tension spring applies a force component downwardly on the drive link substantially along the length of the link to urge the thread pull-off and thread wiper elements into the first extreme position, as illustrated in FIGS. 1 and 2, which is determined by a stop washer 93 having an eccentric bore accommodating the fastening screw 69 so that slight adjustment of the first extreme position may be made. The second component force exerted by the tension spring 90 on the drive linkage tends to turn the link in a clockwise direction about the pivot pin 62, as viewed in FIG. 1, and biases the drive link toward the take-up support disk 27.

The take-up support disk 27 carries a cam member 95 secured to the disk by a pair of fastening screws 96 which pass through elongated slots 97 in the cam member in order to provide for limited adjustment of the cam member on the disk. The cam member 95 projects radially outwardly beyond the periphery of the disk 27 and serves, as illustrated in FIG. 4, to engage the surface 73 on the lateral projection 72 of the drive link when the drive link is released by the latch pin 76 and drawn by the spring 90 against the take-up support disk 27. The cam member 95 will then lift the drive link 71 against the pressure of the tension spring 90, causing both thread-engaging elements 40 and 55 to move from the first to the second extreme position. During this move, which preferably occurs just before the thread is severed, the pull-off element 40 will draw out a length of needle thread and the thread wiper element 55 will move across the path of the needle into a position of readiness to engage the thread. The cam member 95 will then pass beyond the lateral projection 72 and release the drive link for return in response to the tension spring 90 so that the thread-engaging elements of the pull-off and wiper will be returned to the at-rest or first extreme position. During this move, the thread pull-off element 40 will release the quantity of thread which was drawn out, and the thread wiper hooked shaped extremity will engage and withdraw the severed thread end from the work.

Preferably, the thread pull-off and wiper mechanism of this invention may be called into action by a momentary actuation of the solenoid 77. A circuit such as is disclosed and described in the US. Pat. No. 3,386,402, June 4, 1968 to R. J. Ross may be used to energize the solenoid 77 of this invention, with the solenoid 77 being wired in place of the solenoid 2 of the Ross patent. When the solenoid 77 is momentarily actuated, the drive link 71 will be shifted by the spring 90 into a blocking position across the extremity of the latch pin 76 and although the solenoid is de-energized the latch pin is not immediately free to return into effective position. When the drive link is lifted by the cam member 95, as shown in FIG. 4 the shape of the latch surface 75 on the drive link 71 is such as to uncover the latch pin 76 so that it is free to be returned by the compression spring 79. When the drive link 71 is drawn downwardly by the tension spring 90, the latch surface 75 will ride along the latch pin 76 and shift the drive link 71 in a counter-clockwise direction about the pivot pin 62 as viewed in FIG. 1 and the parts will then be in readiness for a subsequent operation.

With this construction, the time of actuation of the solenoid 77 is not critical because actuation of the solenoid releases the drive link 71 into a position of readiness to be operated when the cam member 95 next passes into engagement therewith. The timing of the thread pull-ofi operation and the subsequent thread wiping operation on the needle thread is thus determined by the position of the cam member 95 which is advantageously coordinated with the needle thread take-up member in the manipulation of the needle thread.

Having set forth the nature of this invention, what is claimed herein is:

1. In a sewing machine having an endwise reciprocating thread carrying needle, a needle thread take-up mechanism, and a circularly moving actuator for said needle and take-up mechanism, a needle thread manipulating mechanism comprising thread-engaging means shiftably supported on said sewing machine for movement between two extreme positions, spring means biasing said thread-engaging means toward a first extreme position, a linkage carried on said sewing machine and operatively connected to said thread-engaging means, cam means driven by said circularly moving actuator and engageable with said linkage to drive said thread-engaging means into a second extreme position, and selectively releasable latch means for detaining said linkage out of engagement with said cam means.

2. A needle thread manipulating mechanism as set forth in claim 1 in which said thread-engaging means includes a thread pull-off element and a thread wiping element each shiftably supported on said sewing machine and operated in concert by said linkage, and in which said elements are arranged each to traverse a different segment of the regular needle thread path when moving from one extreme position to another.

3. A needle thread pull-off and wiping mechanism as set forth in claim 2 in which said thread pull-off element e a es and dr ws need] thread fro said re ular nee e read pat?! when driven by saiti cam me ns into said second extreme position, and in which said thread wiping element engages and draws needle thread from said regular needle thread path when returned by said spring means into said first extreme position.

4. A needle thread manipulating mechanism as set forth in claim 1 in which said selectively releasable latch means is operated by an electric solenoid so that the operation of the thread manipulating mechanism is initiated by an electric signal to said solenoid but driven mechanically by said cam means.

5. A needle thread manipulating mechanism as set forth in claim 1 in which said cam means is constrained for movement in a predetermined path in response to said circularly moving actuator and cooperates with a link which is pivotally connected to said linkage, which link extends substantially parallel to the predetermined path of movement of cam means, means defining a cam engaging surface on said link which extends substantially perpendicular to the predetermined path of said cam means so that said link will be shifted substantially endwise by said cam means to drive said thread-engaging means, and in which said selectively releasable latch means detains the cam engaging surface on said link beyond the path of said cam means.

6. A needle thread manipulating mechanism as set forth in claim 5 in which the means for biasing the thread-engaging means toward a first extreme position comprises a single spring which also biases said link into the path of the cam means when the latch means is released, said single spring being arranged to act between said sewing machine frame and said link for applying two components of spring force to said link, one component acting in a direction passing through said pivotal connection of said link with said linkage for biasing said thread-engaging means toward a first extreme position and the other component acting perpendicularly thereto for biasing the cam engaging surface of the link into the path of the cam means.

7. A needle thread manipulating mechanism as set forth in claim 6 in which said selectively releasable latch means comprises a retractable latch pin axially shiftably supported on said sewing machine frame for movement transversely of said link into an extended position across a latch cooperating edge of said link and a retracted position out of engagement with said link, said latch pin when in said extended position being effective to detain said link radially out of the path of said cam means, in which in the spring biased first position of said thread-engaging means the link when released by retraction of the latch pin moves into a blocking position in front of the latch pin, and in which the latch cooperating edge of the linkextends at such an inclination of the length direction of said link that the link will shift out of the blocking position in front of the latch pin when said linkage is driven into said second extreme position.

8. A needle thread manipulating mechanism as set forth in claim 7 in which an electrical solenoid is provided for shifting the latch pin into a retracted position, and spring means is provided for returning the latch pin to extended position. 

1. In a sewing machine having an endwise reciprocating thread carrying needle, a needle thread take-up mechanism, and a circularly moving actuator for said needle and take-up mechanism, a needle thread manipulating mechanism comprising thread-engaging means shiftably supported on said sewing machine for movement between two extreme positions, spring means biasing said threadengaging means toward a first extreme position, a linkage carried on said sewing machine and operatively connected to said threadengaging means, cam means driven by said circularly moving actuator and engageable with said linkage to drive said threadengaging means into a second extreme position, and selectively releasable latch means for detaining said linkage out of engagement with said cam means.
 2. A needle thread manipulating mechanism as set forth in claim 1 in which said thread-engaging means includes a thread pull-off element and a thread wiping element each shiftably supported on said sewing machine and operated in concert by said linkage, and in which said elements are arranged each to traverse a different segment of the regular needle thread path when moving from one extreme position to another.
 3. A needle thread pull-off and wiping mechanism as set forth in claim 2 in which said thread pull-off element engages and draws needle thread from said regular needle thread path when driven by said cam means into said second extreme position, and in which said thread wiping element engages and draws needle thread from said regular needle thread path when returned by said spring means into said first extreme position.
 4. A needle thread manipulating mechanism as set forth in claim 1 in which said selectively releasable latch means is operated by an electric solenoid so that the operation of the thread manipulating mechanism is initiated by an electric signal to said solenoid but driven mechanically by said cam means.
 5. A needle thread manipulating mechanism as set forth in claim 1 in which said cam means is constrained for movement in a predetermined path in response to said circularly moving actuator and cooperates with a link which is pivotally connected to said linkage, which link extends substantially parallel to the predetermined path of movement of cam means, means defining a cam engaging surface on said link which extends substantially perpendicular to the predetermined path of said cam means so that said link will be shifted substantially endwise by said cam means to drive said thread-engaging means, and in which said selectively releasable latch means detains the cam engaging surface on said link beyond the path of said cam means.
 6. A needle thread manipulating mechanism as set forth in claim 5 in which the means for biasing the thread-engaging means toward a first extreme position comprises a single spring which also biases said link into the path of the cam means when the latch means is released, said single spring being arranged to act between said sewing machine frame and said link for applying two components of spring force to said link, one component acting in a direction passing through said pivotal connection of said link with said linkage for biasing said thread-engaging means toward a first extreme position and the other component acting perpendicularly thereto for biasing the cam engaging surface of the link into the path of the cam means.
 7. A needle thread manipulating mechanism as set forth in claim 6 in which said selectively releasable latch means comPrises a retractable latch pin axially shiftably supported on said sewing machine frame for movement transversely of said link into an extended position across a latch cooperating edge of said link and a retracted position out of engagement with said link, said latch pin when in said extended position being effective to detain said link radially out of the path of said cam means, in which in the spring biased first position of said thread-engaging means the link when released by retraction of the latch pin moves into a blocking position in front of the latch pin, and in which the latch cooperating edge of the link extends at such an inclination of the length direction of said link that the link will shift out of the blocking position in front of the latch pin when said linkage is driven into said second extreme position.
 8. A needle thread manipulating mechanism as set forth in claim 7 in which an electrical solenoid is provided for shifting the latch pin into a retracted position, and spring means is provided for returning the latch pin to extended position. 